Oxidation resistance and microstructure of the oxide layers for TiB2-based cermets

The oxidation behaviour of several TiB2 cermets has been studied in air in a range of temperatures between 700 and 1000 degrees C for up to 70 h. The oxidation resistance of these materials has been characterised through measurements of mass gain as a function of time and temperature. The oxidation kinetics of these cermets was observed to change from a parabolic to a linear type at temperatures between 750 and 775 degrees C. Activation energies were observed to be 170-185 and 109-123 kJ mol(-1) for the parabolic and linear ranges, respectively. The oxidation products and the microstructure of the oxide scales formed after these oxidation treatments were characterised by XRD and SEM.